1. Field
The present disclosure relates to a yeast cell capable of producing lactate, a method of preparing the same, and a method of producing lactate using the yeast cell.
2. Description of the Related Art
Lactate is an organic acid which is widely used in various industrial fields such as food, pharmaceutical, chemical, and electronic industries. Lactate is a colorless, odorless, and highly water-soluble substance having low volatility. As lactate is nontoxic to the human body, lactate is used as a flavoring agent, an acidifier, and a preservative. In addition, lactate is a raw material of polylactic acid (PLA), which is an environment-friendly alternative polymer substance and a biodegradable plastic. Technologically, PLA is a polyester resin formed by converting lactate into lactide, which is a dimer, for polymerization, and performing a ring-open polymerization with the lactide. PLA may be processed into various forms such as a film, a sheet, a fiber, and an injection molding product. Therefore, as PLA is a bio-plastic which may extensively be substituted for conventional general-purpose petrochemical plastics such as polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), and polystyrene (PS), the demand for PLA has greatly increased in recent times. In addition, lactate has both a hydroxyl group and a carboxyl group and thus is highly reactive. Thus, lactate may be easily converted to industrially important compounds such as ester of lactate, acetaldehyde, and propylene glycol. Therefore, lactate is drawing attention in the field of chemical engineering as a next-generation alternative chemical raw material.
At present, lactate is industrially produced by a petrochemical synthetic process and a biological fermentative process. In the petrochemical synthetic process, lactate is prepared by oxidizing ethylene derived from crude oil, converting the resulting acetaldehyde into lactonitrile by an addition reaction of hydrogen cyanide, purifying the resulting lactonitrile by distillation, and hydrolyzing the purified lactonitrile by using hydrochloric acid or sulfuric acid. In the biological fermentative process, lactate may be prepared by using assimilable carbohydrates such as starch, sucrose, maltose, glucose, fructose, and xylose as substrates for microbial fermentation to produce lactate. Therefore, despite the existence of these conventional technologies, a microbial strain capable of efficiently producing lactate and a method of producing lactate by using the same are still needed. In accordance with the need, a method of producing lactate by using a microorganism, such as yeast, has been recently developed. However, due to homeostasis of the microorganism, it is difficult for the microorganism to produce only one substance in large quantities.
Thus, there remains a need for yeast cells with increased lactate production capability.